1. Field of the Invention
The present invention relates to an application liquid supply apparatus and an inkjet recording apparatus, and more particularly, to an application liquid supply apparatus and an inkjet recording apparatus which supply an application liquid to an application roller.
2. Description of the Related Art
In an inkjet recording apparatus which forms an image by ejecting ink droplets, if a color image is formed by using inks of a plurality of colors, then there is a possibility that color bleeding occurs. Furthermore, if an image is formed on a recording medium of high permeability, such as normal paper, then there is a possibility that the feathering phenomenon occurs.
Color bleeding or feathering of this kind reduces the quality of the image and therefore preventative measures of various kinds have been proposed. As one such measure, a method is known in which a treatment liquid that aggregates or insolubilizes the coloring material in an ink by reacting with the ink is applied previously to a recording medium, and an image is formed by ejecting ink droplets onto the recording medium to which this treatment liquid has been applied. In this method, the application of the treatment liquid is performed using an application roller or an inkjet head, the treatment liquid being applied to the recording medium by bringing an application roller having treatment liquid deposited on the circumference thereof into contact with the recording medium, or by ejecting treatment liquid onto the recording medium from an inkjet head.
Japanese Patent Application Publication No. 2007-117806 discloses a mechanism for supplying treatment liquid to an application roller, in which an application liquid holding member is placed in contact with the outer circumferential surface of an application roller, treatment liquid is supplied to a space formed on the outer circumferential surface of the application roller (an application liquid holding space) by this application liquid holding member, and the treatment liquid is thereby supplied to the application roller. By means of this mechanism, due to rotation of the application roller, the outer circumferential surface of the roller makes contact with the treatment liquid held in the application liquid holding space, thus supplying treatment liquid to the outer circumferential surface.
If treatment liquid is applied to a recording medium by means of an application roller, then generally the application roller waits at standby in a position separated from the conveyance surface of the recording medium, and is then pressed to make contact with the recording medium in synchronism with the conveyance timing of the recording medium.
However, in Japanese Patent Application Publication No. 2007-117806, since the application roller is not rotated during standby, then the supply of treatment liquid to the application roller is not stable and consequently, there is a possibility that non-uniformities occur in the treatment liquid which has been applied to the recording medium.
On the other hand, if the application roller is rotated during standby, then the treatment liquid supplied from the application liquid holding member is returned directly to the application liquid holding member, and therefore collection of liquid occurs in the region where the liquid returns to the application liquid holding member and this liquid spills over and soils the apparatus. More specifically, since an application liquid holding member is provided in close contact with the outer circumferential surface of the application roller, then if treatment liquid is left on the application roller, this liquid is wiped away by the edge portion of the application liquid holding member when it returns to the application liquid holding member and spills over the rim of same, thus soiling the apparatus.